Flash memory is a non-volatile storage medium, and is a type of electrically erasable programmable read only memory (EEPROM) that can be programmed and erased in large blocks. Flash memories are often used as mass storage devices, such as memory cards, USB flash drives, and MP3 players. Additionally, embedded flash memory is incorporated into an increasing variety of devices. Example applications include smart phones, PDAs (personal digital assistants), computers, digital audio players, digital cameras, mobile phones and console video game hardware, and many others.
Nearly all flash memory integrated circuits include integrated charge pumps. Flash memory uses a high voltage pulse to wipe out any existing data in a particular memory cell before it is written with a new value. Although it is possible to include separate power supplies: (e.g., +5V for reading and +12 V for erasing), more commonly, the higher voltage, used to erase cells, is generated internally by an on-chip charge pump. It is thus possible to provide both voltage levels from one external power supply—(e.g., 1.8 or 3.3V).
However, the charge pump occupies a large are in the integrated circuit (IC). In some cases, the charge pump occupies about 20% of the footprint of the IC.
Methods of facilitating increased use of embedded flash memories are desired.